Road construction is a complex, logistically intensive process. Traditionally, road construction requires a detailed survey of the topography of a desired route and a design profile of a road suitable for the desired route. The desired route may need to be graded to conform to certain standards before any road construction can actually begin. Once a route is graded, surveyors place stakes along the route and mark the desired thickness of the road. String lines are then run from one stake to the next at the marked height. Paving machines use the string lines to control the thickness of the road surface. The actual process of laying pavement may involve a train of machines. The paving train may include a spreader or belt placer to deposit concrete, a slipform paver to extrude the concrete into a slab, a dowel bar inserter to place dowel bars where a slab will be cut, and a texturing and curing machine to place appropriate textures in the road surface.
The machines in a paving train are generally equipped with sensors to follow the string line, and thereby produce a concrete slab having the desired thickness; however, string lines present a number of problems. A string line is only as precise as the number of stakes used to determine the course of the string line. Where the stakes are spaced twenty feet apart the string line represents a single data point every twenty feet. String lines are a physical obstruction. When machines need access to the surface being paved, string lines must be manually taken down and put back. The potential for human error is introduced every time a string line is taken down. Stringless paving technology may address many of the issues inherent in string line paving. Stringless paving utilizes systems other than string lines to control the paving train. Systems for controlling the paving train include Global Positioning System (GPS) satellites, Real Time Kinematics (RTK), and laser leveling.
Furthermore, when planning a pavement project, contractors with detailed surface data can save paving material, reduce the cost of concrete slabs, and reduce the cost of road surface modifications if they predict an overall estimated volume of paving material based on such data and utilize stringless paving techniques to control machines in a paving train.